Doped metal films, e.g., doped metal carbides, nitrides, borides, and silicides, such as aluminum-doped metal carbides, may be used for a variety of applications. For example, aluminum-doped titanium carbide and similar materials may be used for gate electrodes in metal oxide field effect transistors (MOSFETs) or insulated gated field effect transistors (IGFETs), such as complementary metal oxide semiconductor (CMOS) devices, as a barrier layer or fill material for semiconductor or similar electronic devices, or as coatings in other applications.
When used as a layer of an electronic device or as a coating, the doped metal films are typically deposited using gas-phase deposition techniques, such as chemical vapor deposition techniques, including atomic layer deposition. Precursors for the gas-phase deposition often include an organometallic compound (e.g., including aluminum) and a metal halide compound (e.g., including titanium or tantalum). Unfortunately, a decomposition temperature of the organometallic compound can be much lower (e.g., more than 200° C. lower) than the temperature of formation of the desired doped metal film. As a result, precursor decomposition products or residue may form in the deposition reaction chamber during a deposition process. The residue may, in turn, create particles, which result in defects in layers deposited using the reactor. In addition, some of the decomposition products may undergo polymerization in the presence of the metal halide compound, and the polymerization products may result in additional defects in the deposited layers. A number of defects within a deposited layer generally correlates to an amount of material deposited within the reactor; the number of defects within a layer generally increases as a number of deposition runs or amount of material deposited increases.
To mitigate the number of defects in the deposited layer, the reactor may be purged with an inert gas for an extended period of time, on the order of hours, after a certain amount of material is deposited or a number of substrates have been processed. This extended purge process significantly reduces the throughput of the deposition reactor and increases the cost of operation of the reactor.
Accordingly, improved methods and systems for treating a deposition reactor to reduce or mitigate particle formation—such as particles resulting from buildup of precursor decomposition products of materials used to deposit doped metal films—are desired.